The present invention relates to a method for making alkylhalosilanes. More particularly, the present invention relates to a method for making alkylhalosilanes which includes silicon, alkyl halide and copper catalyst.
Rochow, U.S. Pat. No. 2,380,995 discloses preparing a mixture of alkylhalosilanes by a direct reaction between powdered silicon and an alkyl halide in the presence of a copper-silicon alloy. This reaction is commonly referred to as the xe2x80x9cdirect methodxe2x80x9d or xe2x80x9cdirect process.xe2x80x9d The reaction can be summarized as follows: 
where Me is methyl.
In addition to the above methylchlorosilanes, xe2x80x9cresiduexe2x80x9d is also formed during the production of methylchlorosilane crude. Residue means products in the methylchlorosilane crude having a boiling point greater than about 70xc2x0 C., at atmospheric pressure. Residue consists of materials such as disilanes for example, symmetrical 1,1,2,2-tetrachlorodimethyldisilane; 1,1,2-trichlorotrimethydisilane; disiloxanes; disilymethylenes; and other higher boiling species for example, trisilanes; trisiloxanes; trisilmethylenes; etc.
Generally, it is desirable to yield high rates of production in the methylchlorosilane reaction as well as selectively produce dimethyldichlorosilane over the other products. New techniques are constantly being sought to improve the alkylhalosilane reaction.
The present invention provides a method for making alkylhalosilanes comprising reacting an alkyl halide and silicon in the presence of a copper catalyst comprising copper powder, particulated copper, copper flake, or combinations thereof and at least one co-catalyst.